Water Tank Leak

[SnippetySnip]

Hi All,

 

I have a 1996 narrowboat with a stainless steel water tank under the well deck at the bow. The well deck is completely sealed welded steel with a welded in place filler tube for the water tank (starboard side, raised above deck, no seal in play). The tank is accessed from the saloon (behind the stairs) with quite easy to remove ply panels, however, the stove is located on the starboard side so does obstruct easy access on that side. The tank has concrete slabs (ballast) stacked on either side between the hull and the tank.

 

Sadly, I noticed some damp in behind these panels (while doing some other routine maintenance) I've had a brief investigation and the tank itself feels dry (along the front bottom edge), the stopcock and water feed to the pumps feels dry, but there is evidently water getting into this space somehow. I guess options are:

 

• some sort of leak around the filler tube or breather tube that causes a flood when filling, and this water has just sat there in the cold space for a month.
• condensation? none was visible.
• a failure of the stainless tank.
• something else?

 

I'm going to drain the tank and try to dry the area out and will try to investigate further. In the meantime, what thoughts do you all have for troubleshooting this?

 

Alternatively, if I'm in for a trip to a boatyard for a new tank, does anyone have recommendations for reputable places to get this sort of work done (current location Northampton).

 

Many thanks in advance, happy to supply more details!

 

[Tracy D'arth]

Looking on the bright side its most likely to be condensation.  The air around the tank gets warmed in the sun and then the cold wind chills it below the dew point.

[Tony Brooks]

11 minutes ago, Tracy D'arth said:

Looking on the bright side its most likely to be condensation.  The air around the tank gets warmed in the sun and then the cold wind chills it below the dew point.

 

Once again, agreed. Our boat was similar and it suffered badly with condensation there. It may be worse if one is living board in winter.

 

I found that my breather pipe where a lenth of steel tube had been welded to the well deck floor had rusted through and was leaking a bit when filling the tank, but luckily mine was above the floor. An easy fix with a hole saw to cut the steel out and replace with a  compression bulkhead fitting. Not so easy getting the hose on between tank and breather.

 

PS. I fitted a polythene barrier under the ply to help keep damp cabin air out of that area.

Edited March 25 by Tony Brooks

[David Mack]

I think that warm moist air from the cabin can find its way past the plywood panels into the unheated area around the tank, and the water vapour will condense on the cold hull sides, deck plate and water tank. Condensation will not be obvious if you look when the outside temperature is relatively warm, but I bet its there if you look early in the morning or late in the evening.

[blackrose]

The thing to do if you can wait that long is see if the problem persists into summer. If not then it's not a leak. 

[Richard T]

Stainless steel tanks regularly fail at welds. They can flex when being filled. Does your tank bang and bong when being filled?

If it does need to be replaced its not cheap. Ours was replaced this time last year. It entailed cutting out the cockpit floor, cutting up the old tank in situ, replacing with a polypropolene one. Moving filler location and breather, connect to existing water system, replace cockpit floor and repainting. The tank was £660, and vat took the bill to just under £2000. The replacement tank came from Goodwin tanks at Crewe.

[GUMPY]

One of my previous boats used to suffer condensation under the front deck, so much so that once a year at the begining of summer I had to aqua vac the water out from the bilge. 😱

[blackrose]

1 hour ago, Richard T said:

Stainless steel tanks regularly fail at welds. They can flex when being filled. Does your tank bang and bong when being filled?

If it does need to be replaced its not cheap. Ours was replaced this time last year. It entailed cutting out the cockpit floor, cutting up the old tank in situ, replacing with a polypropolene one. Moving filler location and breather, connect to existing water system, replace cockpit floor and repainting. The tank was £660, and vat took the bill to just under £2000. The replacement tank came from Goodwin tanks at Crewe.

 

Suddenly the idea of having to get into my integral tank to clean it out and repaint it doesn't seem so bad...

[Lady M]

Likewise the amount of work involved in putting a 'plastic' water tank in our integral one.  It seemed like a lot at the time but much easier than replacing stainless steel it seems.

[SnippetySnip]

Hi All,

 

First of all, thanks so much to everyone for all the replies and helpful advice and thoughts!

 

I've drained the tank and I'm in a situation where I don't need to fill it for a couple of weeks due to Easter hols. So I'll get the dehumidifier on and try to dry the area out fully. When I fill up I will watch the filler hose and breather and all that. I'll report back in a couple of weeks with an update. Fingers crossed it was just winter condensation!

 

Cheers!

21 hours ago, Tony Brooks said:

 

Once again, agreed. Our boat was similar and it suffered badly with condensation there. It may be worse if one is living board in winter.

 

I found that my breather pipe where a lenth of steel tube had been welded to the well deck floor had rusted through and was leaking a bit when filling the tank, but luckily mine was above the floor. An easy fix with a hole saw to cut the steel out and replace with a  compression bulkhead fitting. Not so easy getting the hose on between tank and breather.

 

PS. I fitted a polythene barrier under the ply to help keep damp cabin air out of that area.

 Fingers crossed that this is the answer!

12 hours ago, Richard T said:

Stainless steel tanks regularly fail at welds. They can flex when being filled. Does your tank bang and bong when being filled?

If it does need to be replaced its not cheap. Ours was replaced this time last year. It entailed cutting out the cockpit floor, cutting up the old tank in situ, replacing with a polypropolene one. Moving filler location and breather, connect to existing water system, replace cockpit floor and repainting. The tank was £660, and vat took the bill to just under £2000. The replacement tank came from Goodwin tanks at Crewe.

Thanks, no bongs or noises like that, and thanks for the heads up on costs, I'm lucky that the only obstacle is the stove, the saloon is otherwise unobstructed, if I do need to remove the tank.

[sueanddaren]

Try a food dye in the tank and see if the wet patch comes out coloured.

[TandC]

If you need a repair or replacement tank, Jay Wolfe Tanks in Kingsthorpe, Northampton are excellent - provided me with two stainless tanks now. 

[blackrose]

On 26/03/2024 at 09:38, SnippetySnip said:

Thanks, no bongs or noises like that, 

 

What about bings and bangs?

[SnippetySnip]

On 02/04/2024 at 06:52, TandC said:

If you need a repair or replacement tank, Jay Wolfe Tanks in Kingsthorpe, Northampton are excellent - provided me with two stainless tanks now. 

Great, thanks for the recommendation. Good to support good local businesses. 

[Ewan123]

On 25/03/2024 at 22:16, blackrose said:

 

Suddenly the idea of having to get into my integral tank to clean it out and repaint it doesn't seem so bad...

It does all sound like a lot of faff doesn't it? Alternatively, I'm pretty sure our stainless steel tank has been in the boat since it was built in 2004 (no marks on any surrounding metal suggesting anything has been cut out to enable access) and still functions perfectly with no maintenance.

On 25/03/2024 at 10:50, SnippetySnip said:

Hi All,

 

I have a 1996 narrowboat with a stainless steel water tank under the well deck at the bow. The well deck is completely sealed welded steel with a welded in place filler tube for the water tank (starboard side, raised above deck, no seal in play). The tank is accessed from the saloon (behind the stairs) with quite easy to remove ply panels, however, the stove is located on the starboard side so does obstruct easy access on that side. The tank has concrete slabs (ballast) stacked on either side between the hull and the tank.

 

Sadly, I noticed some damp in behind these panels (while doing some other routine maintenance) I've had a brief investigation and the tank itself feels dry (along the front bottom edge), the stopcock and water feed to the pumps feels dry, but there is evidently water getting into this space somehow. I guess options are:

 

• some sort of leak around the filler tube or breather tube that causes a flood when filling, and this water has just sat there in the cold space for a month.
• condensation? none was visible.
• a failure of the stainless tank.
• something else?

 

I'm going to drain the tank and try to dry the area out and will try to investigate further. In the meantime, what thoughts do you all have for troubleshooting this?

 

Alternatively, if I'm in for a trip to a boatyard for a new tank, does anyone have recommendations for reputable places to get this sort of work done (current location Northampton).

 

Many thanks in advance, happy to supply more details!

 

Condensation would be my bet as well, I'd actually be surprised if there wasn't any on non-insulated steel surfaces that are kept cold by contact with water (on the other side). If not on the tank, what about the inside of the hull?

 

Also when you say "some damp", how damp is that? Pooling water? Soggy wood? Just a bit visually discoloured? A few photos might assist with suggestions.

[Steve Manc]

On 25/03/2024 at 22:16, blackrose said:

 

Suddenly the idea of having to get into my integral tank to clean it out and repaint it doesn't seem so bad...

Check out Vactan thread to use in water tank to derust it.

[blackrose]

2 hours ago, Steve Manc said:

Check out Vactan thread to use in water tank to derust it.

 

Thanks but I'm not a fan of Vactan having used it previously in my engine room. My water tank is painted with a water-potable epoxy which required properly removing the rust mechanically rather than converting it. I did that 7 years ago so the next time it needs painting it'll be a case of keying the surface of the existing epoxy and adding another couple of coats. If there's any rust those patches will have to go back to bare metal.

[ditchcrawler]

6 hours ago, blackrose said:

 

Thanks but I'm not a fan of Vactan having used it previously in my engine room. My water tank is painted with a water-potable epoxy which required properly removing the rust mechanically rather than converting it. I did that 7 years ago so the next time it needs painting it'll be a case of keying the surface of the existing epoxy and adding another couple of coats. If there's any rust those patches will have to go back to bare metal.

Unless its all peeled off 

[Steve Manc]

11 hours ago, blackrose said:

 

Thanks but I'm not a fan of Vactan having used it previously in my engine room. My water tank is painted with a water-potable epoxy which required properly removing the rust mechanically rather than converting it. I did that 7 years ago so the next time it needs painting it'll be a case of keying the surface of the existing epoxy and adding another couple of coats. If there's any rust those patches will have to go back to bare metal.

Hi Blackrose

What was the result in your engine room?

Thanks 

[blackrose]

On 04/04/2024 at 00:15, Steve Manc said:

Hi Blackrose

What was the result in your engine room?

Thanks 

 

After prepping the engine room floor, swims, uxter plates, etc, with a  wire wheel on an angle grinder I vacuumed it out, wiped over with a damp cloth and used a coat of Vactan to convert any rust that hadn't been removed mechanically. Then went over it with a couple of coats of a Hammerite type direct to metal paint - I can't remember the brand name but it wasn't Hammerite itself. I know that wasn't the best choice of bilge paint but it's what I had so that's what I used. In hindsight having done all that prep I should have bought a can of Jotamastic epoxy.

 

Anyway, about a year later the rust was bubbling back in places where condensation sat around. Perhaps there was a reaction to the xylene thinners in the paint, I don't know. The tannic acid rust converter in Vactan is fine, but I think that the water based polymer matrix is its weakness. It's not a good metal primer which is in effect what it's being used for.

 

On 03/04/2024 at 19:28, ditchcrawler said:

Unless its all peeled off 

 

It hasn't. I opened it up to have a look last autumn. Epoxy doesn't just peel off unless it wasn't applied properly in the first place.

Edited April 5 by blackrose

[ditchcrawler]

2 hours ago, blackrose said:

 

It hasn't. I opened it up to have a look last autumn. 

That's cheating 🤣

[Steve Manc]

Blackrose

 

Thanks for the update. I plan to move forward with just Vactan. I have messaged a member who has done it with acceptable results. Also spoken to the Company who doesn't have any concerns re being the only product in the water tank.

 

Hopefully it will go well. If we have any issues this summer I will give feed back. If not in a few years when I have a look inside the tank.

 

[Alan de Enfield]

53 minutes ago, Steve Manc said:

Hopefully it will go well. If we have any issues this summer I will give feed back. If not in a few years when I have a look inside the tank.

 

If it all goes badly, maybe you could leave a note for your heirs to notify the forum, that it wasn't such a good idea after all.

[Steve Manc]

13 minutes ago, Alan de Enfield said:

 

If it all goes badly, maybe you could leave a note for your heirs to notify the forum, that it wasn't such a good idea after all.

 

Will do 😁 

[blackrose]

1 hour ago, Steve Manc said:

Blackrose

 

Thanks for the update. I plan to move forward with just Vactan. I have messaged a member who has done it with acceptable results. Also spoken to the Company who doesn't have any concerns re being the only product in the water tank.

 

Hopefully it will go well. If we have any issues this summer I will give feed back. If not in a few years when I have a look inside the tank.

 

 

Yes, some people remove the worst of the rust mechanically, vacuum it out, rinse and wetvac it out. Then they apply Vactan to convert the remaining rust without putting any bitumen on top. It's obviously an easier job and even easier the next time you come to do it because you won't have a thick layer of bitumen combined with rust that needs to be removed. However, using Vactan only does require that you check & re-do the job more often, perhaps every 2 or 3 years at the absolute maximum. I definitely wouldn't leave it any longer than 2 years personally.

Edited April 8 by blackrose